30 patients of intermittent ACDS were studied prospectively for a period of 8 weeks to 1 year to evaluate the role of orthoptics in the management of these cases. In patients with convergence insufficiency and a maximum deviation of 25 PD or less the orthoptic treatment was found to be effective in offering symptomatic relief and improving binocular functional status. A reduction in the maximum angle of deviation by 4 PD to 8 PD was observed in 4 patients. Even though the basic angle of deviation remained unchanged in most of the patients, significant functional and symptomatic improvement was obtained in 64% to 85.7% of these cases. The long term stability of these results remains to be studied. In patients with a deviation of more than 25 PD there was no significant improvement in symptoms or reduction in maximum angle of deviation. In 6(37.5%) of these patients some improvement in the fusional range could be demonstrated on the synoptophore without any symptomatic relief.

How to cite this article:Singh V, Roy S, Sinha S. Role of orthoptic treatment in the management of intermittent exotropia. Indian J Ophthalmol 1992;40:83-5

How to cite this URL:Singh V, Roy S, Sinha S. Role of orthoptic treatment in the management of intermittent exotropia. Indian J Ophthalmol [serial online] 1992 [cited 2015 Mar 3];40:83-5. Available from: http://www.ijo.in/text.asp?1992/40/3/83/24394

Intermittent ACDS is one of the commonest form of exodeviation, characterized by periodic divergence of the visual axis of either eye.

Duane[1] considered that such a type of exodeviation results from innervational imbalance (dynamic factors) that upsets the reciprocal relationship between active convergence and divergence mechanisms and this incoordination occurs at the central level, while Bielschowsky[2] considered that it is an anomalous position of rest (determined by certain anatomical and mechanical factors) of the eyeball which contributes to the occurrence of exodeviation. Burian[3] summarized the thinking by stating that the patients with exodeviation have a basic misalignment of their visual axis caused by mechanical and anatomical (static) factors, to which are added innervational (dynamic) factors, that tend to maintain the ocular alignment by con­vergence or to impair it by divergence.

The progress of the whole process from initial exophoria to intermittent ACDS and subsequently to constant ACDS is determined basically by the fusional reserve of the patient and accordingly the disease may be progressive, static or may resolve spontaneously without any treatment[4].

During examination, it is often difficult to determine the sensorial relationship between the two eyes, and each eye seems to be functioning independently[5]. The basic angle shows marked variation when measured at different distances of fixation, at different directions of gaze (Int. ACDS with lateral and vertical incomitance) with and without glasses or by using a +3 D lens (accommodative type of Int. ACDS). Patient may show NRC and ARC simultaneously, there may be a wide variation in fixation pattern i.e. with or without fixation preference or even eccentric fixation (Int. ACDS with mono-fixational syndrome); although hemiretinal suppression develops, amblyopia is rare and there may be a wide variability of fusional reserve and stereoacuity. In view of the intermittent nature of the problem, very often the patients are reluctant to accept as first choice the surgical form of treatment which therefore is avoided or delayed. As an alternative various non surgical approaches to the problem have been tried with varied results. Regarding orthoptic management, a lot of controversy still exists[6]. Many authors[7],[8] deny the role of orthoptic treatment, while others[9],[10] found it to be effective in certain types of int. ACDS only, while still others[11] considered that combined therapy (surgery with orthoptics) is a better approach to attain long term stability of results.

Material and methods

30 patients of intermittent ACDS who attended the orthoptic clinic in the K.G. Medical College, Lucknow during January to December, 1990 and were able to come for periodic evaluation were selected for this study. The patients were subjected to a complete clinical evaluation including detailed history, cycloplegic refraction, corrected and uncorrected visual acuity, cover test for near and distance, prism bar cover test for near and distance, AC/A ratio and orthoptic evaluation on Maddox wing, Maddox Rod, WFDT, RAF near rule and synoptophore. The patients were given proper glasses, antisuppression exercises in the form of part-time (6 hrs/day) weekly alternate occlusion, bar reading exercises, convergence and fusional exercises. Clinical evaluation of symptoms, binocular orthoptic status and maximum angle of deviation was done at 4 weeks, 8 weeks, 12 weeks and at the time of last examination. The conservative management was discontinued after 8 weeks in patients who did not show satisfactory improvement in symptoms and signs. Conservative treatment was continued for a period of 12 weeks to 16 weeks in patients showing satisfactory improvement in symptoms and signs. The period of follow up varied from 8 months to 1 year.

The results of orthoptic management were evaluated on the basis of the following parameters:

(a) Symptomatic relief:

The patients were shown a horizontal line 6 inches long divided into six segments. They were asked to mark on it the amount of symptomatic relief considering that the 6 on the line represented the total symptoms prior to treatment and 0 represented the total relief of symptoms. According to the position of the mark the patients were grouped as follows: 0 to 1 - asymptomatic, 1 to 3 - mildly symptomatic, 3 to 5 - moderately symptomatic and 5 to 6 - no relief in symptoms.

(b) Improvement in binocular functional status:

Good: Phoria with binocular single vision for near or distance or both and binocular functions on the synoptophore.

Fair: Intermittent tropia but improvement in binocular status as shown on the WFDT, synoptophore and effort to control.

Poor: Intermittent tropia with no or minimal improvement in binocular functions on the synoptophore and no improvement in the effort to control.

(c) Change in the maximum angle of deviation on PBCT:

A reduction of 4PD or more was considered significant.

Observations

11 (36.7%) patients in this study were males and 19 (63.3%) were females, the male female ratio being 1:1.7. The mean age at which the patients presented to our clinic was 19.83 years ± 9.07 SD with a range from 5 to 57 years and 15 (50%) patients belonged to the age group 11-21 years. The most frequent complaint [Table - 1] was of eye strain in 16 (53.3%) patients, followed by intermittent squint in 13 (43.3%) patients. Other presenting complaints were headache in 6 (20%) patients, diplopia in 5 (16.6%) cases and photophobia in 2 (6.6%) cases and photophobia in 2 (6.6%) cases. 13 (43.3%) patients had a basic type of exodeviation, 11 (36.7%) had a convergence in­sufficiency type of exodeviation and 6 (20.0%) had a divergence excess type of exodeviation. AC/A ratio when determined by lens gradient method, was high (5) in 7 (23.3%), normal (3 to 5) in 8( 26.6%) and low in 15 (50%) patients. 18 (60%) patients had some amount of convergence insufficiency (ranging from mild to severe) on RAF near rule. 4 (13%) patients had mild amblyopia (corrected visual acuity 6/9 to 6/12). 16 (53.3%) patients were myopic, 9 (30%) were emmetropic, and remaining 5 (16.7%) were hypermdtropic. The maximum deviation as measured by the PBCT was 25 PD or less in 14 (46.7%) patients and more than 25 D in 16 (53.3%) patients.

The sensorial status as assessed on the WFDT revealed BSV at near or distance in 12 (40%) cases and alternate or uniocular suppression in 18 (60%) patients. On the synoptophore no binocular functions could be elicited in 20 (66.6%) patients, although an ability to control the deviation under normal viewing conditions suggested the presence of some degree of binocularity which could not be elicited during the manifest phase. In 10 (33.3%) patients SMP with some degree of fusion and/or stereopsis could be elicited on the synoptophore.

Following orthoptic treatment for 8 wks, 16 (53.3%) patients showed no significant improvement (symptomatic or in the basic angle of deviation). 6 (37.5%) out of these 16 patients revealed some improvement in the fusional range without any symptomatic relief. In all these 16 the orthoptic treatment was discontinued in view of the need for surgical treatment. 14 (46.7%) patients showed improvement following therapy and in this group the orthoptic treatment and follow up was continued as described earlier.

The degree of relief in symptoms at various periods of follow up is represented in [Table - 2]. At 8 wks follow up 6 (20%) patients were asymptomatic, 5 (16.7%) were mildly symptomatic, 3 (10%) were moderately symptomatic and 16 (53.3%) had no relief in symptoms. Orthoptic treatment was dis­continued in these 16 patients. At 12 wks. follow up 10 (71.4%) out of the 14 patients showed marked relief in symptoms and were placed in the asymptomatic group and 2 (14.3%) in the moderately symptomatic group. At the time of last examination even after the orthoptic treatment had been discontinued 8 (57.1%) patients remained asymptomatic, 4 (28.6%) were mildly symptomatic and 2 (14.3%) were moderate­ly symptomatic.

An assessment of the binocular functional status [Table - 3] at 8 wks. follow up revealed good results in 3 (10%) patients, fair results in 6 (20%) patients and poor functional response in 21 (70%) patients. in the 14 patients who received orthoptic treatment after 8 wks. the functional status at 12 wks was similar to that at 8 wks. although some of the patients with fair results had some improvement in the fusional range. At the time of last examination after the orthoptic treatment had been discontinued (14.3%) patients were placed in the category of good, 7 (50%) in fair and 5 (35.7%) in poor functional result group. Despite the fact that 12 (85.7%) patients had a fair or poor functional response as measured on the WFDT and synoptophore some degree of improvement in symptoms was noted in all the patients with a deviation of 25 PD or less.

There was no significant reduction in the angle of deviation in the 16 patients with a deviation of 25 PD. Out of the 14 patients with a deviation of 25 PD or less a significant reduction was observed in 4 (28.6%) patients, 3 of these had a convergence insufficiency type of intermittent ACDS.

Discussion

The role of various forms of orthoptic treatment in the management of intermittent ACDS is widely available in literature. 30 patients of intermittent ACDS were studied prospectively to evaluate the role of orthoptic treatment in their management. The orthoptic treatment was found to have a definite role in the management of intermittent ACDS in patients with convergence insufficiency and a maximum deviation of 25 PD of less. Even though the basic angle of deviation remained unchanged in most of the patients, significant functional and symptomatic improvement was obtained in 64% to 85.7% of these patients. The long term stability of these results is yet to be studied.

Duane A. A new classification of the motor anomalies of the eyes based upon physiological principles, together with their symptoms, diagnosis and treatment. Ann Ophthalmol. Otolaryngol. 5:969.1869;6:94 and 247.1867.